In the DE 20 2004 013 324 U1 an illumination device mounted on the lamellae of a window blind is disclosed. Onto each lamella a light guiding material is applied, which possesses a surface formed of micro-prisms. Each lamella possesses an individual lighting element, injecting an artificial light into the illuminating body. This artificial light is received and deflected by a layer of micro-prisms and thereby illuminating the surrounding of the window blind. Unfortunately, the deflection of the artificial light is defined by the fixed structure of the micro-prisms. Furthermore, the area illuminated by the light emitting window blind is defined through the position and the angle of the lamellae.